1. Field of the Invention
The present invention relates to electronic circuits and more particularly, to an pop noise eliminating circuit that eliminates pop noises when turning on an audio output device.
2. Description of the Related Art
Pop noises may be produced when turning on an audio output device. When turning on an audio output device, the status of the power is unstable, and a pulse will occur. This pulse is misregarded as a sound signal and amplifed by an amplifying circuit, producing pop noises. This problem should be eliminated.
A conventional pop noise eliminator comprises a parallel architecture of two transistors. The pop noise eliminator attempts to eliminate pop noises by means of activating the transistors before starting up power supply.
However, the aforesaid transistor application technique can simply lower the voltage of the pulse. It cannot completely eliminate the pulse. Because the transistors still have therein a bias voltage about 0V˜0.2V. Therefore, a condition of pop noise will still occur.